Pulse collecting method



July 18, 1950 J. F. CLARK, JR

PULSE COLLECTING METHOD Filed Dec. 12, 1947 Qwucmfcvv JOHN F. CLARK JR.

PDnEIDO mw sm OF J- Patented July 18, 1950 UNITED STATES PATENT OFFICE PULSE COLLECTING METHOD John F. Clark, J r., Bethlehem, Pa. Application December 12, 1947, Serial No. 791,446

3 Claims. (01. 250-27) (Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 O. G. 757) This invention relates in general to pulse collecting apparatus and in particular to apparatus for collecting pulse signals from the several stages of a cascaded multivibrator chain or the like.

In the use of pulse transmitted intelligence systems it is frequently desired that a plurality of data be transmitted over a single wire or radio link. Degrees of magnitude or variation of the data furnished by a plurality of instruments is an often-used application of pulse type multiplex systems. In a pulsed system in general and in a telemetering system in particular, the data appear as successively transmitted pulses derived from a chain of multivibrator circuits, with the time spacing between pulses varying with the intelligence.

. An object of this invention is to provide a means for the collection of intelligence pulses from each stage of a cascaded multivibrator chain or the like.

Another object of this invention is to provide a means for the collection of pulses from each stage of a cascaded multivibrator chain or the like, and particularly a means for the prevention of undesired interaction between successive stages and the cancellation or partial cancellation of desired pulses.

Other and further objects of this invention will become apparent from a consideration of the drawings, when taken together with the following detailed description.

In the drawings, the single figure shows a multivibrator chain embodying the invention and demonstrating the collection of pulses by a dual collector tube.

Referring to the figure, there is shown for purposes of illustration a multivibrator chain including a freely-running multivibrator l comprising a pair of regeneratively interconnected tubes a1 and b1. Tube components :11, In of the freely-running multivibrator are used to generate a rectangular type wave which is introduced into the grid of the second multivibrator 2, comprising tubes a2, ha. The frequency of multivibrator I may be selected so that only one pulse at a time is transmitted down the chain, or alternatively it may be selected so that more than one pulse at a time is transmitted down the chain. The circuit of multivibrators 2, 3 and 4 is exemplified as a single stable state, blocked type multivibrator and it should be noted that other circuits of diverse type may be substituted. In the example shown, the right hand tube, 1) series, of each multivibrator 2, 3 and 4 is normally conducting and the left hand tube, a series, is cutofi. {I'D this end the 2 cathodes of the right and left hand tubes of each stage are connected together and returned to ground through a common resistor. The grid of the right hand tube is returned to its cathode to provide zero bias and the grid of the left hand tube is returned to a source of negative blocking voltage typified at 6 in stage 2. The output waveform from the freely-running multivibrator I after differentiation by the RC circuits com prising coupling capacitor C1, C2 and grid and plate resistors R1 and R5 of stage 2 will trigger the tube ha of multivibrator 2 as follows: As tube a1 cuts off and hi on, the resulting drop in plate potential of In is transmitted to the grid of D2 after differentiation, as a negative pulse or peak, which when impressed on the grid of b2 cuts that tube off, and tube (12 on, thus driving multivi-l brator 2 to its unstable state, from which it will recover after draining of the charge from C2 through R1 and the anode supply resistance of R5. These elements form in part the time constant of they unstable state of the multivibrator, and thus determine the duration of the positive pulse produced at the plate of tube b2.

In a similar manner, and at the end of the unstable period of multivibrator 2, the decay of, po.- tential in the plate circuit of in when that tube is turned on again, is transmitted through coupling capacitor C3 as a negative pulse to the right hand tube ha of the next multivibrator. stage 3, thus driving this stage into its unstable state. Then again as this stage returns to its stable state it will drive the succeeding stage 4 into an unstable state and so on down the chain, There is :thus produced from the output of the right hand tubes a series of negative trailing edge pulses, the spacing of which is determined by the time each multivibrator remains in the unstable state in: duced by the negative triggering pulse.

In collecting the successive pulses thus produced by the multivibrator chain the plate of each right hand tube of the several multivibrator stages in the chain is connected through a separate asymmetrical impedance network to a point of collection. Each asymmetrical coupling network is designed to pass unattenuated the negative trailing edges of the pulse output from each of the right hand tubes of the several stages but to suppress the positive leading edges of pulses therefrom. The impedance coupling networks comprise, as herein typified in stage 1, a serially connected diiferentiating condenser CH1 and a half wave rectifier means ll connected to pass negative pulses only from the multivibrator output waveform. The rectifying element II has connected in shunt across it a resistance l2 of suitable value to provide a discharge path to ground for the condenser CID.

As exemplified in the drawing, it may be de- 1 sired under certain operating conditions to use different points of pulse collections for the odd and even numbered stages of the chain. More particularly, the outputs of thefirst, third, fifth,

and all subsequent odd stages are connected to the input grid circuit of the left hand triode section of the dual triode collector tube l3, whereas the outputs of the second, fourth, sixthand all the dual collector tube.

In operation and as the multivibrator stages are driven successively into their unstable states,

thepositive .pulses-developedat theanodesof the right.,hand,.b seriestubes inthe several multivibratorjstages, ,are supplied to and differentiated by the condensers included in the impedance coupling netvrorksand are then applied to their riespectivegrid circuitsoof the dual triode collec'tor 13. The differentiated positively produced pulscsswhich.occursynchronously with the leadingedges ofthe-pulses produced at the pl te f theright hand'tubaiblocktheir respective rectificrs ll and are ,accordinglysharply attenuated asthey reach the input to thecollector tube 13. The differentiated negatively produced pulses which occur synchronously with the trailing edges oflthe pulse ,producedat the output of the right "Finally, the purpose of connecting alternate stages .to separate collector tube grid circuits is to prevent any traces of positive pulses produced attheleading edgesof the positively rising waveformfrom leaking across the shunt resistances I2 or through-the rectifying devices ll and appearing synchronously withand thereby partially cancelling the desired negative pulses, such as wouldoccur 'incoupling successive stages to a common point of collection. If, however, a certai-n amount of cancellation can'be tolerated, a

single collector tube with all output circuits from the chain connected to the grid circuit, may be employed.

Although I have shown only a certain and specific embodiment of the invention it must be understood that I am fully aware that many modifications are possible thereof without departing tromthe spirit 'of-theinvention as defined in the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is: 1. In a cascaded pulse producing multivibrator chain or the like having a plurality of pulse output points therein; the combination of first and second pulse'collection means, and means including a separate asymmetrical impedance network coupling. the oddnumbered output points insaid chain, to the, first collection means and the even numbered output points in said chain to the secondv collection means.

2. In a cascaded pulse producing multivibrator chain or the likehaving a plurality of pulse outputpoints therein; the combination of, first and second pulse collection means, and meansincluding a separate asymmetrical impedance network comprising a unilateral impedance device coupling. the odd nurnbered output points in'said chain to thefirst. collection means and. the even numbered output points in said chain to the secondcollection means.

3. 'In a multiple pulse generating device comprising a plurality of stages of pulse generators connected in cascade relation, each stage having a separate outputpoint; the combination of,first and second. pulse collection means, and means including separate asymmetrical impedance networks coupling the outputs from the odd numbered stages in said pulse generating device to said first collection means and the even nuinbered stages in said device 'to said second collection means.

JOHN F. CLARK, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,303,968 White Dec. 1, 1942 2,390,608 Miller et-al Dec. 11, 1945 2,402,916 Schroeder June 25, 1946 2,403,918 Grosdoff July 16, 1946 2,414,541 Madsen Jan. 21, 1947 2,436,963 Grosdofi Mar. 2, 1948 

